The Influence of Dietary Factors on the Risk of Urinary Stone Formation

The action of various beverages and foods on the composition of the urine in the circadian rhythm and in the 24-hour urine has been investigated under standardized conditions. Orange juice leads to a significant increase of urinary pH and citric acid excretion. Black tea leads to a raised excretion of oxalic acid by only 7.9%. In the short term, beer increases diuresis, but afterwards leads to a compensatory antidiuresis with increased risk of stone formation. Depending on their composition, mineral waters have very different effects on the urinary constituents. Milk as well as cocoa beverage significantly increase calcium excretion; moreover, cocoa causes an increase in the oxalic acid excretion. The leafy vegetable foods containing oxalate, e.g., spinach and rhubarb, lead to peaks of oxalate excretion of 300-400% in the circadian excretion curve. Cheese leads to a significant rise of calcium excretion with acidification of the urine and lowering of citrate excretion. Calcium excretion is increased by 30% by sodium chloride. Foods containing purine result in an increased uric acid excretion over several days. Depending on their phytic acid content, brans bind calcium, but lead to an increased oxalic acid excretion. Analysis of the urine indicates that average diet in Germany entails a high risk of urinary stone formation. As a result of the change to a balanced mixed or vegetarian diet, according to the requirements, significant alterations in urinary pH, calcium, magnesium, uric acid, citric acid, cystine, and glycosaminoglycan excretion are measured, resulting in a drastic reduction in the risk of urinary stone formation

Variability in urinary oxalate measurements between six international laboratories

Background. Hyperoxaluria is a major risk factor for kidney stone formation. Although urinary oxalate measurement is part of all basic stone risk assessment, there is no standardized method for this measurement. Methods. Urine samples from 24-h urine collection covering a broad range of oxalate concentrations were aliquoted and sent, in duplicates, to six blinded international laboratories for oxalate, sodium and creatinine measurement. In a second set of experiments, ten pairs of native urine and urine spiked with 10 mg/L of oxalate were sent for oxalate measurement. Three laboratories used a commercially available oxalate oxidase kit, two laboratories used a high-performance liquid chromatography (HPLC)-based method and one laboratory used both methods. Results. Intra-laboratory reliability for oxalate measurement expressed as intraclass correlation coefficient (ICC) varied between 0.808 [95% confidence interval (CI): 0.427-0.948] and 0.998 (95% CI: 0.994-1.000), with lower values for HPLC-based methods. Acidification of urine samples prior to analysis led to significantly higher oxalate concentrations. ICC for inter-laboratory reliability varied between 0.745 (95% CI: 0.468-0.890) and 0.986 (95% CI: 0.967-0.995). Recovery of the 10 mg/L oxalate-spiked samples varied between 8.7 ± 2.3 and 10.7 ± 0.5 mg/L. Overall, HPLC-based methods showed more variability compared to the oxalate oxidase kit-based methods. Conclusions. Significant variability was noted in the quantification of urinary oxalate concentration by different laboratories, which may partially explain the differences of hyperoxaluria prevalence reported in the literature. Our data stress the need for a standardization of the method of oxalate measuremen

The role of salt abuse on risk for hypercalciuria

<p>Abstract</p> <p>Background</p> <p>Elevated sodium excretion in urine resulting from excessive sodium intake can lead to hypercalciuria and contribute to the formation of urinary stones. The aim of this study was to evaluate salt intake in patients with urinary lithiasis and idiopathic hypercalciuria (IH).</p> <p>Methods</p> <p>Between August 2007 and June 2008, 105 lithiasic patients were distributed into 2 groups: Group 1 (n = 55): patients with IH (urinary calcium excretion > 250 mg in women and 300 mg in men with normal serum calcium); Group 2 (n = 50): normocalciuric patients (NC). Inclusion criteria were: age over 18 years, normal renal function (creatinine clearance ≥ 60 ml/min), absent proteinuria and negative urinary culture. Pregnant women, patients with intestinal pathologies, chronic diarrhea or using corticoids were excluded. The protocol of metabolic investigation was based on non-consecutive collection of two 24-hour samples for dosages of: calcium, sodium, uric acid, citrate, oxalate, magnesium and urinary volume. Food intake was evaluated by the three-day dietary record quantitative method, and the Body Mass Index (BMI) was calculated and classified according to the World Health Organization (WHO). Sodium intake was evaluated based on 24-hour urinary sodium excretion.</p> <p>Results</p> <p>The distribution in both groups as regards mean age (42.11 ± 10.61 vs. 46.14 ± 11.52), weight (77.14 ± 16.03 vs. 75.99 ± 15.80), height (1.64 ± 0.10 vs. 1.64 <b>± plusorminus </b>0.08) and BMI (28.78 ± 5.81 vs. 28.07 ± 5.27) was homogeneous. Urinary excretion of calcium (433.33 ± 141.92 vs. 188.93 ± 53.09), sodium (280.08 ± 100.94 vs. 200.44.93 ± 65.81), uric acid (880.63 ± 281.50 vs. 646.74 ± 182.76) and magnesium (88.78 ± 37.53 vs. 64.34 ± 31.84) was significantly higher in the IH group (p < 0.05). There was no statistical difference in calcium intake between the groups, and there was significantly higher salt intake in patients with IH than in NC.</p> <p>Conclusions</p> <p>This study showed that salt intake was higher in patients with IH as compared to NC.</p

Is Excess Calcium Harmful to Health?

Most current guidelines recommend that older adults and the elderly strive for a total calcium intake (diet and supplements) of 1,000 to 1,300 mg/day to prevent osteoporosis and fractures. Traditionally, calcium supplements have been considered safe, effective and well tolerated, but their safety has recently been questioned due to potential adverse effects on vascular disease which may increase mortality. For example, the findings from a meta-analysis of randomized controlled trials (currently published in abstract form only) revealed that the use of calcium supplements was associated with an ~30% increased risk of myocardial infarction. If high levels of calcium are harmful to health, this may alter current public health recommendations with regard to the use of calcium supplements for preventing osteoporosis. In this review, we provide an overview of the latest information from human observational and prospective studies, randomized controlled trials and meta-analyses related to the effects of calcium supplementation on vascular disease and related risk factors, including blood pressure, lipid and lipoprotein levels and vascular calcification

Metabolic diagnosis and medical prevention of calcium nephrolithiasis and its systemic manifestations: a consensus statement

Background: Recently published guidelines on the medical management of renal stone disease did not address relevant topics in the field of idiopathic calcium nephrolithiasis, which are important also for clinical research. Design: A steering committee identified 27 questions, which were proposed to a faculty of 44 experts in nephrolithiasis and allied fields. A systematic review of the literature was conducted and 5216 potentially relevant articles were selected; from these, 407 articles were deemed to provide useful scientific information. The Faculty, divided into working groups, analysed the relevant literature. Preliminary statements developed by each group were exhaustively discussed in plenary sessions and approved. Results: Statements were developed to inform clinicians on the identification of secondary forms of calcium nephrolithiasis and systemic complications; on the definition of idiopathic calcium nephrolithiasis; on the use of urinary tests of crystallization and of surgical observations during stone treatment in the management of these patients; on the identification of patients warranting preventive measures; on the role of fluid and nutritional measures and of drugs to prevent recurrent episodes of stones; and finally, on the cooperation between the urologist and nephrologist in the renal stone patients. Conclusions: This document has addressed idiopathic calcium nephrolithiasis from the perspective of a disease that can associate with systemic disorders, emphasizing the interplay needed between urologists and nephrologists. It is complementary to the American Urological Association and European Association of Urology guidelines. Future areas for research are identified

Variability in urinary oxalate measurements between six international laboratories

Hyperoxaluria is a major risk factor for kidney stone formation. Although urinary oxalate measurement is part of all basic stone risk assessment, there is no standardized method for this measurement

Assessing Dysferlinopathy Patients Over Three Years With a New Motor Scale

The Jain COS Consortium.[Objective] Dysferlinopathy is a muscular dystrophy with a highly variable clinical presentation and currently unpredictable progression. This variability and unpredictability presents difficulties for prognostication and clinical trial design. The Jain Clinical Outcomes Study of Dysferlinopathy aims to establish the validity of the North Star Assessment for Limb Girdle Type Muscular Dystrophies (NSAD) scale and identify factors that influence the rate of disease progression using NSAD.[Methods] We collected a longitudinal series of functional assessments from 187 patients with dysferlinopathy over 3 years. Rasch analysis was used to develop the NSAD, a motor performance scale suitable for ambulant and nonambulant patients. Generalized estimating equations were used to evaluate the impact of patient factors on outcome trajectories.[Results] The NSAD detected significant change in clinical progression over 1 year. The steepest functional decline occurred during the first 10 years after symptom onset, with more rapid decline noted in patients who developed symptoms at a younger age (p = 0.04). The most rapidly deteriorating group over the study was patients 3 to 8 years post symptom onset at baseline.[Interpretation] The NSAD is the first validated limb girdle specific scale of motor performance, suitable for use in clinical practice and clinical trials. Longitudinal analysis showed it may be possible to identify patient factors associated with greater functional decline both across the disease course and in the short-term for clinical trial preparation. Through further work and validation in this cohort, we anticipate that a disease model incorporating functional performance will allow for more accurate prognosis for patients with dysferlinopathy. ANN NEUROL 2021;89:967–978The estimated US $4 million needed to fund this study was provided by the Jain Foundation. (www.jain-foundation.org) The Jain COS consortium would like to thank the study participants and their families for their invaluable contribution. The John Walton Centre Muscular Dystrophy Research Centre is part of the MRC Centre for Neuromuscular Diseases (Grant number MR/K000608/1).Peer reviewe